The difference between the 3 alternative in Mountlake Terrace really only effect the southwest corner of the City as all alternatives proposed to serve the MLT Transit Center and then head norht adjacent to I-5.

The Aurora alternative would have the alignment come east on Ballinger Way from Aurora and then cross the freeway to the Transit Center. The I-5 alternative would run up I-5 and have little effect on surrounding properties. The 15th Ave NE would have the greatest effect on MLT properties since it proposed to go through Gateway Plaza and use the Evergreen Elementary property to get to the Transit Center.

Here are some of the advantages/disadvantages of each of the alternatives from Seattle Transit Blog as well as a map:

I-5 Alignment (Red)

Runs along the side of I-5, switching from the east side to the west side around the county line.

Stations at NE 145th and NE 185th. These station areas are fairly constrained by single family neighborhoods (and a golf course at NE 145th) with very little space for P&R garages and virtually no TOD potential.

End to end travel time is lowest.

This alignment roughly splits the difference between the high demand corridors of Aurora Ave and Lake City Way, requiring all riders to either drive or transfer from a feeder bus.

Because of I-5?s ramps, sound walls, detention ponds, limited ROW, and bridges, I could see this alignment being more complex and costly than one would expect.

Aurora Ave Alignment (Blue)

Runs up Aurora Ave after transitioning over from Northgate Station somewhere between NE 103rd and NE 130th. At SR-104 it would turn east and meet up with I-5 at Mountlake Terrace.

Although Sound Transit previously identified only two stations, I believe three stations along Aurora Ave makes more sense.

The first station after Northgate would probably serve the Bitter Lake neighborhood at or around NE 130th.

The second stations would probably serve the Aurora Square Shopping center and Shoreline Community College somewhere around NE 155th to NE 160th.

The third station could be somewhere between NE 185th and SR-104.

End to end travel time would probably be 1-3 minutes longer than the I-5 alignment.

These stations have enormous TOD potential, with large underutilized and under-performing commercial lots that are perfect for significant upzoning and redevelopment on the scale of Bel-Red corridor of East Link. Bitter Lake has already seen significant senior housing development in the area.

The width of the road and commercial character make an elevated alignment down the corridor viable, which would be required to maintain reasonable travel times.

From a network design perspective I particularly like an Aurora alignment because it seamlessly merges Seattle’s two largest North/South transportation corridors. Despite Aurora and I-5?s close proximity — roughly a mile — connections between the corridors are horrible, especially for transit riders.

15th Ave Alignment (Green)

Runs up 15th Ave probably via Pinehurst Way N. The north end of this alignment conveniently joins with I-5 close to Mountlake Terrace.

Sound Transit is looking at two stations, probably at NE 145th and NE 175th. These are largest activity nodes along the corridor.

The issue paper says this alignment will take 4 additional minutes compared to I-5 — even with an elevated alignment, which doesn’t make sense to me.

This alignment a mixed bag, with less extreme disadvantages but also few large advantages. For example this alignment has modest TOD potential compared to Aurora but won’t have the same P&R opportunities as I-5.

15th Ave is a narrow corridor with single family housing all along the corridor, making an elevated line fairly hard politically.

From a long range planning perspective, 15th Ave is bad. It puts Link in an awkward, no mans land; it’s half-way between I-5 and Lake City Way. This creates problems similar what Martin wrote about yesterday in the Rainer Valley.

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